List of top Physics Questions

In a mixture of gases, the average number of degrees of freedom per molecule is 6. If the rms speed of the molecule is \(c\), what is the velocity of sound in the gas?
A proton enters a uniform magnetic field $\vec{B} = 0.5 \hat{k} \ \text{T}$ with velocity $\vec{v} = 10^6 \hat{i} \ \text{m/s}$. The magnitude of the magnetic force on the proton is:
The half-life of a radioactive substance is 4 hours. If initially there are 256 grams, how much remains after 10 hours?
The electric field in a plane electromagnetic wave is given by \(E_z = 60 \cos(5x + 1.5 \times 10^{10} t)\) V/m. Then expression for the corresponding magnetic field (\(B_y\)) is (here subscripts denote the direction of the field) is:
An electron (mass \(9 \times 10^{-31}\) kg and charge \(1.6 \times 10^{-19}\) C) moving with speed \(c/100\) (\(c\) = speed of light) is injected into a magnetic field of magnitude \(9 \times 10^{-4}\) T perpendicular to its direction of motion. We wish to apply a uniform electric field \( \vec{E} \) together with the magnetic field so that the electron does not deflect from its path. (speed of light \(c = 3 \times 10^8\) m/s):
A simple pendulum has a time period of 2 s on Earth's surface. What is its time period at a height equal to the Earth's radius (R)? (Acceleration due to gravity at height h is \( g_h = \frac{g}{(1 + h/R)^2} \)).
The escape velocity from the surface of a planet is \(v_e\). What will be the escape velocity from a planet whose mass and radius are twice that of the original planet?
A ball is thrown vertically upward with a speed of 49 m/s. How long will it take to return to the thrower’s hand?
An electromagnetic radiation of wavelength 331.5 nm is made to strike the surface of a metal. Electrons are emitted with a kinetic energy of \(1.2 \times 10^5\) J mol\(^{-1}\). The work function (in eV) of the metal is (h=\(6.63 \times 10^{-34}\) Js, \(N_A = 6 \times 10^{23}\) mol\(^{-1}\))
A particle is moving with a constant velocity of 5 m/s in a circular path of radius 2 m. What is the centripetal acceleration of the particle?
The pair of physical quantities not having the same dimensions is:
If electrons of mass 'm' and de Broglie wavelength '$\lambda$', incident on a metal plate in an X-ray tube, then the minimum wavelength of X-rays emitted is
(h = Planck's constant and c = Speed of light in vacuum)
A coil has 200 turns and an area of \( 0.01 \, \text{m}^2 \). If the magnetic field changes from 0 to 0.5 T in 0.1 seconds, what is the induced emf in the coil?
A charged particle moves in a magnetic field with velocity $ v $ perpendicular to the field $ B $. The radius of the circular path is $ r $. Which of the following expressions gives the charge $ q $ of the particle?
What are the charges stored in the 1 µF and 2 µF capacitors in the circuit as shown in the figure once the current (\( I \)) becomes steady?
A person wearing a parachute jumps off a plane from a height of 2 km from the ground and falls freely for 20 m before his parachute opens. After his parachute opens if he continues to move uniformly with the velocity attained due to his freefall, the total time taken by the person to reach the ground is (Acceleration due to gravity = 10 ms$^{-2}$)
An alpha particle and a deuterium ion are accelerated through the same potential difference. These are then directed towards a target nucleus to make a head-on collision. It is observed that their distance of closest approach is the same. Justify it theoretically.

Consider two infinitely large plane parallel conducting plates as shown below. The plates are uniformly charged with a surface charge density \( +\sigma \) and \( -\sigma \). The force experienced by a point charge \( +q \) placed at the mid point between the plates will be:

A convex lens has focal length 20 cm. An object is placed at a distance of 40 cm from the lens. What is the position of the image formed?
A 12 V battery connected to a 6 \(\Omega\), 10 mH coil through a switch drives a constant current in the circuit. The switch is suddenly opened. Assuming that it took 1 ms to open the switch, the average emf induced across the coil would be
If the radiation emitted by a perfect radiator has maximum intensity at a wavelength of 2900 Å, the intensity of radiation emitted by it is (Stefan-Boltzmann's constant = \(5.67 \times 10^{-8}\) Wm\(^{-2}\)K\(^{-4}\) and Wein's constant = \(2.9 \times 10^{-3}\) mK)
Match List - I with List - II.
Angular Impulse
Choose the correct answer from the options given below:
The expression given below shows the variation of velocity \( v \) with time \( t \): \[ v = At^2 + \frac{Bt}{C + t}. \] The dimension of \( ABC \) is:
The potential difference between points C and D of the electrical circuit shown in the figure is
A pipe has a radius of 2 cm at one end and 1 cm at the other end. The velocity of the water at the wider end is 5 m/s. What is the velocity of the water at the narrower end, assuming incompressible flow?